Chrome will turn colors when exposed to high heat. They start with yellowish/brown, then go to blue.

Is this something new? i.e. has it been normal chrome for a long time and suddenly turned yellow? If so, then you potentially have another problem with your engine, perhaps a lean condition causing the exhaust gas temperature to be too high.

You can get things re-chromed, yes, but if the same condition exists as turned the current ones yellow, the new chrome will turn colors as well.